Invader Zim is an American animated television series created by Jhonen Vasquez and originally aired on Nickelodeon. The recurring cast includes voice actors Richard Steven Horvitz, Rodger Bumpass, Kevin McDonald (The Kids in the Hall) and John de Lancie (Star Trek: The Next Generation). Vasquez voices parts in the show. The show was cancelled early in its run and some episodes were unfinished. The show ran for two seasons before its cancellation.
Invader Zim (voiced by Richard Steven Horvitz,Billy West in the pilot and Melissa Fahn as a newborn in his flashback of "Parent-Teacher Night") is an incompetent Irken invader, who is foul-tempered, overzealous, impulsive, megalomaniac and convinced of his own greatness. He dreams of regaining his leaders' trust by taking part in Operation Impending Doom II, so Zim is assigned to Earth, a planet which the Almighty Tallest believe has little to no chance of existing. However, against all odds, Zim makes it to Earth and establishes a base on a fake conquest mission. Because of his very small stature, Zim disguises himself as a human child using a hairpiece to cover his antennae and contact lenses to make his eyes look normal.
No one realizes that Zim is an alien, except Dib and Gaz. Zim has no friends, and physically harms other kids like in "Dark Harvest", when he takes their organs and replaces them with gadgets, if they attempt to befriend him. However, they will always defend him when Dib calls him an alien. He is equipped with a PAK, a backpack with, (among other gadgets,) long, retractable robotic spider legs that enable him to move about quickly and climb almost any obstacle.
Zim constantly schemes to enslave or destroy mankind, and despite his access to potent Irken technology, his plans are never successful. Zim also has a high opinion of himself, and will sometimes refer to himself in the third person.